How to deploy to github with file pattern on travis?

Wildcards are supported by now if you enable the file_glob option. This is how I deploy a build .deb file to GitHub releases:

before_deploy:
  - export RELEASE_PKG_FILE=$(ls *.deb)
  - echo "deploying $RELEASE_PKG_FILE to GitHub releases"
deploy:
  provider: releases
  api_key:
    secure: YOUR_ENCRYPTED_API_KEY
  file_glob: true
  file: "${RELEASE_PKG_FILE}"
  on:
    tags: true

Setting up is easy by executing travis setup releases with a dummy filename and modifying .travis.yml afterwards.